Fast Mixing Condensation Nucleus Counter: Application to Rapid Scanning Differential Mobility Analyzer Measurements

Condensation nucleus counters (CNCs) exhibit slower time response than expected due to mixing effects within the detector.This mixing produces an exponential distribution of delay times with a characteristic mixing time m that ranges from 0.1 s to 0.9 s for commonly used instruments and limits their usefulness for measuring rapidly changing aerosols. Moreover, when used as detectors in the scanning electrical mobility spectrometer (SEMS; also known as scanning mobility particle sizer, SMPS), CNCs limit the speed with which size distribution measurements can be made. In order to overcome this limitation, a new, fast-response mixing CNC (MCNC) has been developed and characterized. The time response of this new detector and TSI Models 3025 and 3010 CNCs has been measured using a spark source to generate an aerosol pulse. The mixing induced response smearing of this new detector, m , of this instrument is 0.058 s, which is significantly shorter than either of the other instruments tested. Its lower detection limit is about 5 nm diameter. The high aerosol flow rate of the MCNC (0.65 l min -1 ), fast time response, and low detection limit make it an ideal detector for SEMS/SMPS measurements. Using this MCNC as a detector for the SEMS, size distribution measurements over the 5 nm to 140 nm range have been made in 3 s with minimal distortion. The size distribution of a coagulation aerosol was effectively recovered by deconvolution with scans as short as 1 s. Uncertainties in the 1 s scans result, in part, from electronics problems in the scanning DMA.     

Characterization of titanium aluminide alloy components fabricated by additive manufacturing using electron beam melting

Intermetallic, γ-TiAl, equiaxed, small-grain (～2 μm) structures with lamellar γ/α₂-Ti₃Al colonies with average spacing of 0.6 μm have been fabricated by additive manufacturing using electron beam melting (EBM) of precursor, atomized powder. The residual microindentation (Vickers) hardness (HV) averaged 4.1 GPa, corresponding to a nominal yield strength of ～1.4 GPa (～HV/3), and a specific yield strength of 0.37 GPa cm³ g^?1 (for a density of 3.76 g cm^?3), in contrast to 0.27 GPa cm³ g^?1 for EBM-fabricated Ti–6Al–4V components. These results demonstrate the potential to fabricate near net shape and complex titanium aluminide products directly using EBM technology in important aerospace and automotive applications.     

An Efficient Stochastic Clustering Auction for Heterogeneous Robotic Collaborative Teams

Stochastic Clustering Auctions (SCAs) constitute a class of cooperative auction methods that enable improvement of the global cost of the task allocations obtained with fast greedy algorithms. Prior research had developed Contracts Sequencing Algorithms (CSAs) that are deterministic and enable transfers, swaps, and other types of contracts between team members. In contrast to CSAs, SCAs use stochastic transfers or swaps between the task clusters assigned to each team member and have algorithm parameters that can enable tradeoffs between optimality and computational and communication requirements. The first SCA was based on a “Gibbs Sampler” and constrained the stochastic cluster reallocations to simple single transfers or swaps; it is applicable to heterogeneous teams. Subsequently, a more efficient SCA was developed, based on the generalized Swendsen-Wang method; it achieves the increased efficiency by connecting tasks that appear to be synergistic and then stochastically reassigning these connected tasks, hence enabling more complex and efficient movements between clusters than the first SCA. However, its application was limited to homogeneous teams. The contribution of this work is to present an efficient SCA for heterogeneous teams; it is based on a modified Swendsen-Wang method. For centralized auctioning and homogeneous teams, extensive numerical experiments were used to provide a comparison in terms of costs and computational and communication requirements of the three SCAs and a baseline CSA. It was seen that the new SCA maintains the efficiency of the second SCA and can yield similar performance to the baseline CSA in far fewer iterations. The same metrics were used to evaluate the performance of the new SCA for heterogeneous teams. A distributed version of the new SCA was also evaluated in numerical experiments. The results show that, as expected, the distributed SCA continually improves the global performance with each iteration, but converges to a higher cost solution than the centralized SCA. The final discussion outlines a systematic procedure to use SCA in various aspects of the application of multi-robot cooperative systems.     

Long term fixation for histological studies.

It was found that a glutaraldehyde-formalin-phosphate buffered fixative could preserve retinal tissue for light microscopy, even if the tissue remained in the fixative for a month. Retinal tissue that previously was difficult and expensive to procure could now be obtained.     

The application of cationic fixing agents to cotton dyed with direct dyes under different pH conditions

The effect of application pH on the effectiveness of the conventional cationic fixing agents Matexil FC-ER and Fixogene CXF in improving the wash fastness of the commercial direct dyes CI Direct Red 89, CI Direct Yellow 106 and CI Direct Blue 85 on cotton has been investigated. While the recommended neutral pH application resulted in improved fastness of the dyeings to the ISOC06/C2 wash fastness test, wash fastness was noticeably better when the fixing agents were applied under alkaline conditions.     

1‐MCP does not improve the shelf‐life of Chinese cabbage

Chinese cabbages cv ‘Yuki’ (Brassica campestris L ssp pekinensis (Lour) Olsson) were treated with air containing 1‐methylcyclopropene (1‐MCP) at concentrations ranging from 0 to 1 µl l^?1 for 12 h at 22°C before storage for 9 weeks at 3°C. Quality, weight loss and trimming loss were measured before treatment, and before and after storage, but were not influenced by 1‐MCP. 1‐MCP at 0.1 and 1.0 µl l^?1 elicited increased levels of respiration and ethylene production which subsided when the cabbages were placed in cold storage. Copyright © 2004 Society of Chemical Industry     

Identification and characterization of a mutation, in the human UDP-galactose-4-epimerase gene, associated with generalized epimerase-deficiency galactosemia

Epimerase-deficiency galactosemia results from impairment of the human enzyme UDP-galactose-4-epimerase (hGALE). We and others have identified substitution mutations in the hGALE alleles of patients with the clinically mild, peripheral form of epimerase deficiency. We report here the first identification of an hGALE mutation in a patient with the clinically severe, generalized form of epimerase deficiency. The mutation, V94M, was found on both GALE alleles of this patient. This same mutation also was found in the homozygous state in two additional patients with generalized epimerase deficiency. The specific activity of the V94M-hGALE protein expressed in yeast was severely reduced with regard to UDP-galactose and partially reduced with regard to UDP-N-acetylgalactosamine. In contrast, two GALE-variant proteins associated with peripheral epimerase deficiency, L313M-hGALE and D103G-hGALE, demonstrated near-normal levels of activity with regard to both substrates, but a third allele, G90E-hGALE, demonstrated little, if any, detectable activity, despite near-normal abundance. G90E originally was identified in a heterozygous patient whose other allele remains uncharacterized. Thermal lability and protease-sensitivity studies demonstrated compromised stability in all of the partially active mutant enzymes.     

Image systems engineering education in an electronic classroom

Digital imaging technologies have now developed to the point where engineers specializing in image systems engineering are needed in order for imaging to reach its full potential, In 1996, the University of Iowa launched a multiphase project for the development of a well-structured interdisciplinary image systems engineering curriculum with both depth and breadth in its offerings. This project has been supported by equipment grants from the Hewlett Packard Company. The new teaching approach that we are developing is very dissimilar to the blackboard-and-chalk approach we used in previous years. Utilizing a 40-seat electronic classroom, lectures consist of presentation of concepts, immediately followed by examples, and practical exploratory problems. Four image processing classes have been offered in the new collaborative learning environment during the 1996-1997 academic year. This paper outlines the employed educational approach we are taking and summarizes our experience in the first year     

A Review of Multiple Criteria Analysis for Water Resource Planning and Management

Multiple criteria analysis (MCA) is a framework for ranking or scoring the overall performance of decision options against multiple objectives. The approach has widespread and growing application in the field of water resource management. This paper reviews 113 published water management MCA studies from 34 countries. It finds that MCA is being heavily used for water policy evaluation, strategic planning and infrastructure selection. A wide range of MCA methods are being used with the fuzzy set analysis, paired comparison and outranking methods being most common. The paper also examines the motivations for adopting MCA in water management problems and considers future research directions. This study was funded by the eWater CRC ().